Process of producing vat dyestuffs of the isodibenzanthrone series



Patented Nae; 192a a b736 6 EDUARD EoLzArFEL' mi) orronmun'snonr, or EocHs'r-oN-rnE-mm, GER, assrenons T emrmnamnms worms, me, on NEW Y0, N. Y., A. coaromsalon or nnnswsnn v rnocEiss or rnon'ucme var DYES'I'UFFS or THE rsonmnguzmrnnonn sERIEs It'o Drawing. Ajpficatioifiledfiecember 16,1926, Serial 1T0. 155,331, and in Germany December 18, 1925. I

Our present invention relates to a new proc- 50 parts of this oxidation product are intros ess'of preparing va't dyestuffs of: the benzanduced at SO-100 G. into a melt of 50 parts throne series. I otcaustic potash and 50 parts of ethyl alcohol In application(Ser. No.- 61,775 filed 00- and the wholeis stirred at this temperature tober 10, 1925, in the names of Paul N awiasky, until the reaction is complete. The melt is 55 5 EduardHolzapfel and Otto Braunsdorf) vat dissolved in water and air is assed through dyestuffs are described which can beobtained the liquid until there is no yestufi left in I bytreating benzanthronyl sulfides or other solution in the form of its leuco compound.

thioethers of benzanth'rone,-or derivatives The mass is then filtered and thoroughly thereof, with alkaline condensing agents. washed with water. The dyestufi thus 010- 60 Now we have found that the oxidation tained is isodibenzanthrone, which is practiproducts derived from benzanthronyl-thiocally free from. dibenzanthrone. It may, if

ethers and having a sulfoxide or sulfone charnecessary, be further urifie'd by the known acter can be converted sometimes with still methods for instance y treating it with an greater facility, into valuable vat dyestufi's organic solvent.

bymeans of alkaline condensing agents. The reaction most probably proceeds as Y The following exaniplesserve to illustrate cordingto the followingquation:

our invention, but they are not intended to f If the oxidation process is carried out with -limit it thereto, all parts being by weight. nitric. acid in sulfuric acid or nitrobenzene,

1. 50 parts of 'Bz'-l-Bz-l-benzanthronylsul-' there are obtained products of the same char-.. fid'e are dissolved in 500 parts of sulfuric acid acter as that of the above described product of 95% strength, and there are gradually which, however, contain nitrogen. They are added thereto, while coolin with ice, 10 robably nitroderivatives and arecapable of 40 parts of hydrogen peroxide 0 30% strength. ing reduced to the corresponding amino When the reaction is complete, themelt which derivative These amino derivatives yield,

' is at first bluishreen shows a deep yelldwishwhen condensed with alcohol and caustic potbr'own color. The mass is then poured on ice, ash, violet-blue vat dyestuifs containing'nitrofiltered by suction and washed until neutral; gen:

'45 The'oxidation' product is a brownish-yellow 2. 100 parts of Bz -l Bz l' benzanthronyl- I powder, which dissolves in hot nitrobenzene sulfide areintroduced at ordinary tem eratoa brown solution with a red fluorescence. tureg while stirrin into 1000 parts of sul- The color oi its solution in concentrated sulfuric. acid of 66 there is then added a 'furic acid i's yellowish-brownwithayellowish mixture of 50 parts of nitric acid and 150- 50 'fluorescence'if" t parts of concentrated sulfuric acid so slowly a blue vat with red that there is no considerable rise of temperature. 'After having further stirred the mass for some hours, it is poured on ice, the brownish-yellow precipitate is drawn off by suction, washed until neutral and dried. The reaction product is a brownish-yellow powder which dissolves in concentrated sulfuric v acid to a yellowish-olive solution. On heating this so lution its color changes to blue or bluishviolet. Analysis of the product shows that it is most probabl a dinitrobenzanthronylsulfone, which can be converted into the corresponding diamino derivative by treating it with a diluted solution of sodium sulfide at the temperature of the water bath. This diamino derivative is a reddish-brown powder, which dissolves in concentrated sulfuric acid to an olive-green solution which, when heated, changes to bluish-green.

By melting this product with caustic potash and ethyl alcohol at 13,0140 C. a darkblue vat dyestufi is obtained which gives fluorescence from which cotton is dyed blue tints with a violet hue. On chlorination, the color changes into a marine-blue. In concentrated sulfuric acid the dyestufi dissolves to a green solution.

It corresponds most probably to the formula We claim: 1. The process which comprises treating a compound of the general formula:

wherein the benzanthrone nuclei may be substituted and n, stands for 1 or 2, with an alkaline metal hydroxide.

2. The process which comprises heating a compound of the general formula:

- wherein the benzanthrone nuclei may be substitued and 'n. represents 1 or 2, with an alkaline metal hydroxide in the presence of an aliphatic alcohol of low molecular weight.

3. The process which comprises treating a compound of the general formula:

o-eo

wherein n stands for 1 or 2, with an alkaline metal hydroxide.

4. The process whichcomprises heating diamino-benzanthronylsulfone of the most probable formula:

-* o o o o g In testimony whereof, we aflix our signatures.

EDUARD HOLZAPFEL. OTTO BRAUNSDORF. 

